99 ram 2500 pickup a/c switches to defrost under load
#1274121
07/25/12 11:51 PM
07/25/12 11:51 PM
|
Joined: Jul 2007
Posts: 34 Concord Twp. Ohio
62 crown
OP
member
|
OP
member
Joined: Jul 2007
Posts: 34
Concord Twp. Ohio
|
Hi guys, I'm sure someone has already dealt with this one, but I haven't...Yet My 99 ram's a/c blows nice and cold, until you put your foot into it, then it switches to defrost, which sucks..I thought about locking the ducts vaccum switches, but there is probably a better fix available. any suggestions ?? Thanks, Mike
62 Imperial Crown 63 Dodge 880 67 Satellite 69Roadrunner 70Roadrunner 78 Lil Red Express 81 Powerwagon 82 Grand Wagoneer 99 RAM 2500 4X4 08 RAM 2500 4X4
|
|
|
Re: 99 ram 2500 pickup a/c switches to defrost under load
[Re: 62 crown]
#1274122
07/26/12 12:07 AM
07/26/12 12:07 AM
|
Joined: Apr 2006
Posts: 209 Carlisle, AR.
mdwyer
enthusiast
|
enthusiast
Joined: Apr 2006
Posts: 209
Carlisle, AR.
|
Look at the vac line at the firewall as it goes into the cab (plastic line pass side) I would bet it has a nice worn spot in it causing a leak. Have had to fix this twice on my 3500.
mike
1970 Challenger T/A 1970 Roadrunner RM21 Vcode 1971 Gtx 1971 Satellite 1971 Charger 500 GB5 383 A54 car 1972 Satellite 1997 Dodge 1500 hunting rig 2014 Ram 2500 Mega Cab
|
|
|
Re: 99 ram 2500 pickup a/c switches to defrost under load
[Re: MoparMarq]
#1274124
07/26/12 01:22 PM
07/26/12 01:22 PM
|
Joined: Jan 2004
Posts: 4,576 Motor City
6PKRTSE
master
|
master
Joined: Jan 2004
Posts: 4,576
Motor City
|
My 96' 2500 Ram does the same thing. It has done it for years. I have just dealt with it. I guess, I'll look at the vac line going into the cab as suggested. I saw a TSB before that had a diagram of which vac line needed an additional vac valve installed o cure the problem. I tried that as the diagram showed but then it stayed on defrost 100% of the time no matter where the switch was. So, I removed it.
1963 Belvedere 440 Max Wedge Tribute 1970 Charger R/T S.E. 440 Six Pack 1970 Challenger R/T, 528 Hemi 1970 Charger 500 S.E. 440 4 BBL 1970 Plymouth Road Runner 383 1974 Chrysler New Yorker 440 1996 2500 RAM 488 V-10 4X4 2004 3500 Dually Cummins 4x4 2012 Challenger R/T Classic.
|
|
|
Re: 99 ram 2500 pickup a/c switches to defrost under load
[Re: 62 crown]
#1274125
07/26/12 02:21 PM
07/26/12 02:21 PM
|
Joined: Jan 2003
Posts: 25,902 Rio Linda, CA
John_Kunkel
Too Many Posts
|
Too Many Posts
Joined: Jan 2003
Posts: 25,902
Rio Linda, CA
|
The factory says:
Vehicle Application: 1996 Dodge Ram 1500 5.2L, GAS, Vin Y, Eng Cfg V8 1999 Dodge Ram 3500 Van 5.9L, GAS, Vin Z 1998 Dodge Ram 1500 5.2L, Vin Y, Eng Cfg V8 2000 Dodge Ram 1500 Pickup 5.9L, Vin Z, Eng Cfg V8 1998 Dodge Ram 1500 5.9L, Vin Z, Eng Cfg V8 2001 Dodge Ram 1500 Pickup 5.2L, Vin Y, Eng Cfg V8 1999 Dodge Ram 1500 Van 5.2L, Vin Y, Eng Cfg V8 2001 Dodge Ram 1500 Pickup 5.9L, Vin Z, Eng Cfg V8
Customer Concern: Driving with the A/C on under light or heavy acceleration, the airflow will stop blowing out of the vent ducts and switch to blowing out of the defrost vents.
Tests/Procedures: 1. Check the vacuum check valve at the right side of the intake manifold and check the second check valve in the line to the left of the receiver drier.
2. If they are good, check for a leaking line or defective and leaking vacuum motor in the Heater Ventilation Air Conditioning (HVAC) system.
Potential Causes: Plastic Line Vacuum Check Valve Vacuum Motor
Tech Tips: When vacuum is lost to the system as in acceleration, the HVAC system will switch to the defrost position as a safety default.
Diagnostic Codes: None
The INTERNET, the MISinformation superhighway
|
|
|
Re: 99 ram 2500 pickup a/c switches to defrost under load
[Re: John_Kunkel]
#1274126
07/26/12 11:41 PM
07/26/12 11:41 PM
|
Joined: Jan 2003
Posts: 1,379 Houston,Tx.
Lee446
pro stock
|
pro stock
Joined: Jan 2003
Posts: 1,379
Houston,Tx.
|
I have been trying to fix my 96 Ram 1500 for two years, I did everything listed, changed out all check valves and hoses, tested all the vac motors... no luck. I finally decided to pull out the A/C control switch, the vac lines run to it and it directs the vac to the appropriate vac motors. When I took it apart, you could see that this flat molded rubber gasket has raised ribs on it that seal the various passages so that the vac goes to the correct ports when it moves laterally. The gasket looks like it has shrunk about 10%. It also is lubricated with a grease like lubriplate and was dried out. I cleaned the surfaces and relubed it and reassembled it as a Hail Mary play. When I put in service, I ended up having to push up on the knob and stick a toothpick under it to wedge it up, but it works like a champ, no more dropping out on acceleration and my recirc setting works again which lets my A/C blow 11* colder. I called the dealer as this is a dealer only item and found that you cannot buy just the switch, you have to buy the whole panel assembly with temp setting and blower speed etc. This is about $160, so I think I will wait till winter gets here. It has worked perfectly for a couple of weeks now. Hope this helps and if you try it and it works for you, let us know!
|
|
|
Re: 99 ram 2500 pickup a/c switches to defrost under load
[Re: gtx6970]
#1274129
08/06/12 12:51 AM
08/06/12 12:51 AM
|
Joined: Jul 2007
Posts: 34 Concord Twp. Ohio
62 crown
OP
member
|
OP
member
Joined: Jul 2007
Posts: 34
Concord Twp. Ohio
|
Well, I still haven't had time to actually work on the truck, but I needed to use it this weekend, and was not willing to sweat my ass off again, so here's the way to get the A/C to blow out of the vents in the dash....Look under the dash, above the gas pedal, and you'll see the vaccum canister that controls the ducts. Hook up your Mighty Vac vaccum pump, and give it a few squeezes...and whattaya know, the vents blow cold air out again. If you need Defrost, release the vaccum pump, and out the defroster ducts it goes. I know this is half assed, but for a quick temproairy fix, this is the way to go.... Mike
62 Imperial Crown 63 Dodge 880 67 Satellite 69Roadrunner 70Roadrunner 78 Lil Red Express 81 Powerwagon 82 Grand Wagoneer 99 RAM 2500 4X4 08 RAM 2500 4X4
|
|
|
Re: 99 ram 2500 pickup a/c switches to defrost under load
[Re: Lee446]
#1274131
08/11/12 05:11 PM
08/11/12 05:11 PM
|
Joined: Jul 2007
Posts: 34 Concord Twp. Ohio
62 crown
OP
member
|
OP
member
Joined: Jul 2007
Posts: 34
Concord Twp. Ohio
|
Do you think that rubber gate could be repaired ??? How about some of the liquid rubber that you dip your tool handle into....just a thought. I still haven't had a chance to get into mine yet, too many other things on the to do list...Mike
62 Imperial Crown 63 Dodge 880 67 Satellite 69Roadrunner 70Roadrunner 78 Lil Red Express 81 Powerwagon 82 Grand Wagoneer 99 RAM 2500 4X4 08 RAM 2500 4X4
|
|
|
|
|